The enclosure is located on a hill composed of sandstones of the St Maughans Formation[4] with an elevation of 807 ft (246 m), about 0.8 miles (1.3 km) east of the confluence of the Rivers Usk and Honddu in the centre of Brecon.

[1] The hillfort can be accessed by a public footpath which joins Slwch Lane north of the site and loops around the rampart.

[2] The hillfort is smaller than the one on nearby Pen-y-crug[3] and is irregular but roughly rectangular in shape, measuring about 187 m by 242 m, with a single encircling rampart.

[5] A small church stood for some time at Slwch Tump, marking the place where Saint Eluned was supposedly beheaded.

Eluned was one of the daughters of the 5th-century King Brychan of Brycheiniog and, as a Christian, she refused a pagan prince's marriage proposal and fled from him.